1. Field of the Invention
The present invention relates to an apparatus and a method for detecting an eye in image data obtained in chronological order by picking up images of a face and tracking the detected eye, an apparatus and a method for judging the open/close state of the detected eye, and a computer memory product.
2. Description of Related Art
One of apparatuses to assist driving of a vehicle such as a car is an apparatus for picking up images of a driver's face with a vehicle-mounted camera positioned so as to pick up images of the driver's face, detecting the position of the driver's eye in the obtained image data and tracking the detected eye, which apparatus is suggested in Japanese Patent Application Laid-Open No. 2000-163564, for example.
Such an apparatus is generally constructed to store image data of an area including a detected eye of a driver when the eye included in image data are detected in image data obtained with the vehicle-mounted camera and comparing this image data with image data obtained sequentially while the vehicle is running, so as to detect an eye area in the image data obtained sequentially and, further, to perform an eye tracking process.
It is required in such a structure to sequentially store image data of an eye area detected in image data, which is to be used for detecting an eye in image data sequentially obtained in chronological order. Consequently, huge memory capacity will be required for storing the all image data of an eye area. Moreover, since areas which correlate closely with each other are selected from the respective image data obtained sequentially, a long time is required for a process of detecting an eye in subsequent image data.
Moreover, there is a problem that it is impossible to realize a process of tracking an eye in image data obtained sequentially when an area which does not include an eye is improperly detected as an eye area in the image data.
Another one of apparatuses to assist driving of a vehicle such as a car is an apparatus for converting image data obtained with the vehicle-mounted camera into binary data, detecting an eyeball area of a driver on the basis of the generated binary image data and judging the open/close state of the eye on the basis of the vertical width of the detected eyeball, which apparatus is suggested in Japanese Patent Application Laid-Open No. H6-32154 (1994), for example. Such an apparatus can detect the driver falling asleep at the wheel, so that it is also possible to construct a system to give warning to the driver asleep at the wheel.
Such an apparatus judges the open/close state of an eye by detecting the vertical width of an eye area in image data which has been converted into binary data. Consequently, there arises another problem that a difference in the vertical width of an eye between the open state and the closed state becomes small when the eyelashes are long or the eye is narrow, and it is difficult to judge the open/close state of the eye.